Monarch Butterflies

Those of us who read Flight
Behavior by Barbara Kingsolver were interested in Verlyn
Kinkenborg’s column
this morning about the monarch butterflies.

The novel is about a family in Apalachia who find a remote area
of their farm covered in butterflies one Spring morning. It’s
because of a fictional change to the pattern of monarch
butterfly migration.

The column is about what we now know about the real reasons for
the decline in the monarch butterfly population. He writes:

One recent study suggests that the long-term survival of the species may be in doubt. A few weeks ago, one of the scientists devoted to studying monarchs, Ernest Williams at Hamilton College, summarized for me the threats that have been reported in recent studies.

Nearly every link in the monarchs’ chain of being, he said, is at risk. Illegal logging in Mexico has reduced their winter habitat — an already vanishingly small area, which is itself being altered by the warming climate. Ecotourists who come to witness the congregation of so many butterflies disturb the creatures they have come to see. But perhaps most damaging is the demise of milkweed.

Monarchs have the misfortune to rely exclusively on a plant that farmers all across the Midwest and Northeast consider a weed. There is a direct parallel between the demise of milkweeds — killed by the herbicide glyphosate, which is sprayed by the millions of gallons on fields where genetically modified crops are growing — and the steady drop in monarch numbers.

To anyone who has grown up in the Midwest, the result seems very strange. After decades of trying to eradicate milkweed, gardeners are being encouraged to plant it in their gardens, and townships and counties are being asked to let it thrive in the roadside ditches. What looks like agricultural success, purging bean and corn fields of milkweed (among other weeds), turns out to be butterfly disaster.